Update json module to jsonutils

oslo project provide jsonutils, and tacker use it in many place[1],
this PS to update the remained json module to oslo jsonutils for
consistency.

[1]: https://github.com/openstack/tacker/search?q=jsonutils&unscoped_q=jsonutils

Change-Id: I7254f80bab9cfb9fed0f1e7841003dea47aec9e7

lower-constraints.txt

@@ -45,7 +45,7 @@ oslo.config==5.2.0
 oslo.context==2.22.0
 oslo.i18n==3.20.0
 oslo.log==3.36.0
-oslo.serialization==2.25.0
+oslo.serialization==2.18.0
 oslo.utils==3.36.0
 oslosphinx==4.7.0
 packaging==17.1

requirements.txt

@@ -8,6 +8,7 @@
 #
 # PBR should always appear first
 oslo.log>=3.36.0 # Apache-2.0
+oslo.serialization!=2.19.1,>=2.18.0 # Apache-2.0
 pbr!=2.1.0,>=2.0.0 # Apache-2.0
 python-tackerclient>=0.8.0 # Apache-2.0
 

tacker_horizon/openstack_dashboard/dashboards/nfv/vnffgmanager/views.py

@@ -10,12 +10,11 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-import json
-
 from django.urls import reverse
 from django.urls import reverse_lazy
 from django.utils.translation import ugettext_lazy as _
 from oslo_log import log as logging
+from oslo_serialization import jsonutils
 
 from horizon import exceptions
 from horizon import forms
@@ -93,7 +92,7 @@ class DetailView(tabs.TabView):
 
         try:
             vnffg = tacker_api.tacker.get_vnffg(self.request, vnffg_id)
-            vnffg["vnffg"]["mgmt_url"] = json.loads(
+            vnffg["vnffg"]["mgmt_url"] = jsonutils.loads(
                 vnffg["vnffg"]["mgmt_url"]) if vnffg["vnffg"].get(
                 "mgmt_url") else None
             return vnffg

tacker_horizon/openstack_dashboard/dashboards/nfv/vnfmanager/views.py

@@ -12,12 +12,11 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-import json
-
 from django.urls import reverse
 from django.urls import reverse_lazy
 from django.utils.translation import ugettext_lazy as _
 from oslo_log import log as logging
+from oslo_serialization import jsonutils
 
 from horizon import exceptions
 from horizon import forms
@@ -95,8 +94,8 @@ class DetailView(tabs.TabView):
 
         try:
             vnf = tacker_api.tacker.get_vnf(self.request, vnf_id)
-            vnf["vnf"]["mgmt_url"] = json.loads(vnf["vnf"]["mgmt_url"]) if \
-                vnf["vnf"]["mgmt_url"] else None
+            vnf["vnf"]["mgmt_url"] = jsonutils.loads(vnf["vnf"]["mgmt_url"]) \
+                if vnf["vnf"]["mgmt_url"] else None
             return vnf
         except ValueError as e:
             msg = _('Cannot decode json : %s') % e